(1) Field of the Invention
The present invention refers to dentistry and in particular to orthodontic intervention tools in which the main element consists of a direct view rigid video-endoscope installed on an articulated and compensated arm. Such a device is intended mainly but not exclusively for orthodontic interventions, and allows the dental surgeon to work under control using a video screen and carries out the functions of an intra-oral and extra-oral video camera, of a directable lighted mirror, of a transilluminator, of a negatoscope, of a saliva-removing pump, and in some cases advantageously replaces the polymerizing lamp and the shadow-free operating lamp.
(2) Description of Related Art
With video cameras for the oral cavity of the prior art the greatest difficulties for the dental surgeon who works with the video-screen control derive, on the one hand from the difficulty in synchronizing one's owns movements with the image on the screen and on the other hand the difficulty in focusing the image itself on the tooth upon which he intervenes.
It must be kept in mind that to work in comfort on a tooth only looking at the image transmitted on the control video its necessary on the one hand that the image of the tooth on the screen is directed in the same way as what the dentist usually sees, with or without his hand-held mirror, in the mouth of the patient, on the other hand that the image of the tooth sits in a fixed position on the screen, and only the image of the tool moved by the dentist must have the possibility of moving round the tooth to end up with the image of the point upon which the intervention must take place.
To get to the point upon which the intervention must take place the dentist must therefore move the image-taking aperture of the video-endoscope so that the image of the field of vision on the control video-screen simultaneously comprises the part of tooth to be treated and the image of the distal end of the work tool which he holds, without the image of the tool blocking that of the point to be reached on the tooth to be treated.
Moreover, the current state of the art does not allow images of the distal faces of teeth—in other words those furthest from the image-taking point—to be taken with a direct view rigid video-endoscope, at the base of the oral cavity of the patient, this is not currently possible due to the size of rigid video-endoscopes available on the market. It is therefore necessary to apply to deviated view rigid video-endoscopes according to the known art.
On the video-endoscope according to the present invention deviated vision is obtained with a tube sleeve which completely surrounds the optical tube and can rotate with respect to it.
When the dental-surgeon manoeuvres a deviated vision video-endoscope to move the image-taking aperture in order to look for the best imaging angle to work on a tooth, the angle made by the plane of the CCD, the abbreviation commonly used to indicate a charge-coupled device, of the video-endoscope with the plane of the field of vision continually changes which has the consequence, on the control screen, of modifying the addressing of the images of the tooth observed and of making the dentist lose his references, who therefore finds it very difficult to position the image of the end of his tool on the image of the precise point of the tooth which he tries to reach.
Such a change in addressing of the image of the tooth, on the control screen, between two positions of the image-taking aperture is the result of the product of a rotation and of a homotethy, i.e. of a biunique correspondence between segments of superposing planes. Such a homotethy is direct or indirect depending upon the respective relative positions of the distal end of the tool which the dental surgeon is holding, of the tooth having its image taken and of the image-taking aperture of the video-endoscope.
It follows from this that, when the dentist who intervenes on a tooth using video control, he moves—from a given working angle—the image-taking aperture to look for a different angle of view and that if he wishes to continue his work in favourable conditions, he must re-establish the position of the tooth in the direction which it occupied previously. For this, it is necessary that one makes an opposite displacement, in other words the inverse product of the rotation and of the homotethy which modified the position of the image of the tooth passing from the starting position to the end position of the image-taking aperture, to the new image of the tooth which appears on the screen. The device according to the present invention is directed to allow the user to carry out in favourable conditions such a rotation and such a homotethy, direct or inverse, through the combined action of a micromotor which makes the CCD rotate about its axis and of an electronic plate which inverts the addressing of the signals at the level of the CCD, which has the consequence of inverting the images from left to right and from bottom to top. To operate in comfort, moreover, using video control it is necessary that the image-taking aperture is neither misty nor blocked by splashes of water or by solid particles deposited in it. The device according to the invention provides a solution to this problem supplying, at the distal end of the endoscope, on the image-taking aperture, a suitable air flow also when the deviated vision sleeve rotates upon itself.
As outlined above, a further condition must be satisfied to operate in favourable conditions using video control: it is necessary that the image of the visualised object is in a fixed position on the screen. The device according to the invention provides a solution to this problem by associating with the video-endoscope an articulated and compensated arm upon which said video-endoscope is fastened with a pawl.
On the other hand, in the prior art the dental surgeon must face the economic and economic problems posed by the multiplication of tools around the dentist's chair, tools which are, nevertheless, indispensable for carrying out the profession.